Optical design of the high-energy resolution beamline at a dipole magnet of BESSY II

We report on the optical design of a dipole-magnet beamline to be implemented at the new storage ring facility BESSY II. For this beamline, which is dedicated to high-energy resolution photoemission and photoabsorption research, calculated spectral resolution, grating efficiencies, and photon flux in the whole photon-energy range of operation from 30 to 1500 eV are presented. The Petersen-type plane-grating monochromator operating with collimated light ensures a superior performance of the beamline in either the higher-order suppression mode or the high-energy resolution mode by a proper choice of the deviation angle at the plane grating.